The present invention generally relates to abnormality monitoring system which monitors the state of a plant with use of an industrial television camera or cameras (ITV cameras).
Techniques related to the present invention are disclosed in the following published Japanese applications:
(1) JP-A-6304396
An ITV camera, picture processing means and memory means for previously storing a normal picture representing a normal state are used to monitor an abnormality in a plant.
(2) JP-A-61-30192
For the purpose of monitoring a moving crane, transported packages, etc, a mark is applied as a target to a moving object or a relatively moving object, and the moving object is traced to discriminate and judge the movement pattern or size of the moving object.
(3) JP-A-58-51679
When detecting an abnormality, the contents of the abnormality are displayed in the form of a picture, message and so on.
(4) JP-A-60-93589
When one ITV camera becomes faulty, operation is switched from the faulty camera to another normal ITV camera.
(5) JP-A-61-116489
An abnormality is detected on the basis of projection distributions in x- and y-directions of a display screen.
(6) JP-A-62086990
When detecting an abnormality, informs the operator indicates the occurrence of the abnormality by issuing an alarm sound from a loudspeaker or by blinking a lamp.
These related techniques, however, have inherent problems in that no consideration is given to the influence of a camera positioning error caused by a single ITV camera monitoring a plurality of locations or to a relative positional shift between the camera and the object to be monitored caused by the vibration of a plant to be monitored or by the vibration of the camera. In this regard, a shift between an input monitor picture zone in a monitor state and a normal monitor picture zone (previously set picture zone) in a normal state prevents correct detection of an abnormality.
Further, since different monitoring priorities (monitoring importances) are not provided to objects to be monitored, the monitoring efficiency becomes low.
In addition, even when an abnormality is detected, only such means as will inform the operator of the occurrence of the abnormality in the form of an alarm sound or simple message is provided and no device is provided to allow even a beginner to take countermeasures against the abnormality.
Furthermore, since not two but only one is provided for each of the processing devices of the abnormality monitoring system, the overall monitoring system is insufficient with respect to safety and security against the occurrence of a fault in the system itself, that is, the reliability in the detection of the abnormality is low.